This invention relates to disposable packages for holding small, typically single-use quantities of a liquid material containing a volatile solvent, and to methods of making such packages.
By way of specific illustration, the invention will be particularly described with reference to the packaging of a unit-of-use quantity of nail enamel, together with an applicator. Such packaging constitutes one important field of use of the invention, which, however, in its broader aspects is not limited thereto.
It would be desirable to provide nail enamel in disposable unit-of-use packages (also conveniently containing a disposable applicator) for sale or promotional distribution, e.g. as samples to enable a customer to try out an enamel without having to invest in the purchase of a large quantity. Necessary or advantageous attributes of a package of this type include low cost, infrangibility, good sealing of the contained enamel, extended shelf life, ease of opening for use, attractive appearance, and ability to bear externally visible imprints of an informative and/or decorative nature.
Commercial nail enamel formulations include volatile solvents such as toluene, isopropyl alcohol, ethyl acetate, and butylacetate, together with other chemical compounds. Owing particularly to the volatile solvent content, these formulations attack plastics commonly used for disposable packaging. Thus, while conventional plastic blister packages as currently employed for a wide variety of consumer products offer advantages with respect to cost, secure sealing, resistance to breakage, and ability to be imprinted with designs and information, their use to package nail enamel has heretofore been precluded. An additional problem with blister packages is that rupture of the seal is often difficult; if a blister package contains a liquid, difficulty in opening the package is likely to cause spillage.
Accordingly, nail enamel in consumer quantities is usually packaged in glass. Sample amounts of nail enamel must at present be provided in glass vials which contain much more product than is required for single-use sampling, yet are so small as to require an attached paperboard carrier to bear printed information and descriptions of use; the high cost of such sample packaging has been prohibitive for many manufacturers.
Similar considerations are applicable to the packaging, and especially unit-of-use or sample packaging, of other liquid products that contain volatile solvents, e.g. other cosmetic materials, paints, etc.